1. Field
The present invention relates to a device for displaying an engine rotational speed on a tachometer included in a motorcycle, and particularly to an engine rotational speed display device capable of making display without causing a sense of incongruity even when the engine rotational speed varies sharply in a case of electrically displaying the engine rotational speed.
2. Description of the Related Art
Conventionally, when an engine rotational speed display device electrically displays the rotational speed of an engine, crankshaft rotational speed pulses generated by the rotation of a crank pulse rotor provided to the crankshaft of the engine are detected by a rotational speed sensor. The engine rotational speed is calculated on the basis of a moving average of detected values of the crankshaft rotational speed pulses.
Such an engine rotational speed display device causes a phenomenon in which variation in accuracy of the rotational speed sensor when the engine rotational speed is in a low rotational speed range affects the display of the rotational speed, and impairs the ease of visually checking the display of the rotational speed. Accordingly, in order to prevent occurrence of such a phenomenon, the length of a determination time for calculating a moving average is changed according to whether the engine rotational speed is high or low. When the engine rotational speed is low, the engine rotational speed is displayed with the determination time lengthened to standardize the variation. When the engine rotational speed is high, response in a case of displaying the engine rotational speed is improved by shortening the determination time. An example of such related art can be found in Japanese Patent Laid-Open No. Hei 01-154195.
Although the above-described engine rotational speed display device has an effect in determining a steady-state engine rotational speed, there occurs a delay in the display of the engine rotational speed immediately after the rotational speed varies sharply, for example immediately after the engine is stopped, and in the display of the engine rotational speed when the engine is stopped due to an inappropriate starting operation of an MT vehicle, for example. The display of the engine rotational speed is not immediately changed to “0” even though the engine is stopped, thus causing a sense of incongruity to the driver. Therefore sufficient provisions have not been made for sharp variations in the engine rotational speed.